Apparatus and method for image group integrity protection

ABSTRACT

A system and method for protecting the integrity of a group of images is provided. One embodiment for protecting the integrity of a group of images comprises watermarking each one of a plurality of images in an image group with a unique watermark having at least an image digest, the image digest comprising information that identifies the watermarked image as an original image, and the plurality of images having a predefined order in the image group; and including in selected ones of the unique watermarks a unique decryption key, each one of the unique decryption keys configured for decrypting the unique watermark of a next image in the image group.

TECHNICAL FIELD

[0001] The present invention is generally related to imageryauthentication and, more particularly, is related to a system and methodfor protecting the integrity of an image group comprised of a pluralityof images.

BACKGROUND OF THE INVENTION

[0002] In digitally based image capturing devices an image or“photograph” of an object is stored in a digital data format in thememory within, or coupled to, the image capturing device. A nonlimitingexample of a image capturing device is the digital camera that capturesstill images and/or video images. Captured images are stored in a memorythat resides within or is coupled to the digital camera.

[0003] Watermarking and other tampering detection techniques are knownin the art for protecting the integrity of individual images. Thewatermarking and tamper detection techniques allow confirmation that theimage has not been altered or otherwise tampered with.

[0004] However, groupings of images can be altered or otherwise tamperedwith. Potential alteration of a group of images includes the removal ofone or more images from the group, the addition of one or more images tothe group, and/or the replacement of one or more images of the group.

[0005] For example, a group of images may be captured by the police at acrime scene. During the investigation and/or trial, it would be veryundesirable if one or more of the original images were “lost” from thegroup, if one or more images not from the original group of images wereadded to the group, or if one or more original images were replaced. Ifany such occurrence were to occur to the group of images, individualimage watermarking might fail to detect added, missing or replacedimages.

[0006] Another nonlimiting example includes electronic archiving ofdocuments. For example, images of public records such as propertyassignment documents filed at a public office may be digitally copiedand stored electronically. Thus, a group of images could establish achain of title for the property. During a title search, it would be veryundesirable if one or more of the images were “lost” from the group, ifone or more images not from the group of images were added to the group,or if one or more images were altered. If any such occurrence were tooccur to the group of original images, individual image watermarkingtechniques might fail to detect added, missing or replaced images.

SUMMARY OF THE INVENTION

[0007] The present invention provides a system and method for protectingthe integrity of a plurality of images. Briefly described, inarchitecture, one embodiment for protecting the integrity of a group ofimages comprises watermarking each one of a plurality of images in animage group with a unique watermark having at least an image digest, theimage digest comprising information that identifies the watermarkedimage as an original image, and the plurality of images having apredefined order in the image group; and including in selected ones ofthe unique watermarks a unique decryption key, each one of the uniquedecryption keys configured for decrypting the unique watermark of a nextimage in the image group.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The components in the drawings are not necessarily to scalerelative to each other. Like reference numerals designate correspondingparts throughout the several views.

[0009]FIG. 1 is a block diagram of an embodiment of an image groupwatermarking system implemented in a digital camera.

[0010]FIG. 2 is a block diagram of an embodiment of image groupwatermarking system implemented in a digital camera, and anotherembodiment of image group watermarking system implemented in personalcomputer.

[0011]FIG. 3 illustrates four images having watermarks in accordancewith an embodiment of the present invention.

[0012] FIGS. 4A-D is a flowchart illustrating a process used by anembodiment of the image group watermarking system.

[0013] FIGS. 5A-C is a flowchart illustrating a process used by anembodiment of the image group watermarking system.

DETAILED DESCRIPTION

[0014] The present invention, an image group watermarking system,provides a system and method for protecting the integrity of a pluralityof images that are grouped together into an image group. Integrity ofthe image group is effected by watermarking each image in the imagegroup in accordance with the present invention.

[0015] For convenience, an “image” is defined herein to include any ofthe various forms of digital information corresponding to an image thatis captured by a image capture device, such as, but not limited to,digital cameras, facsimile (FAX) machines, copy machines, or the like.When a watermark is incorporated onto the image by the image groupwatermarking system in accordance with the present invention, thedigital information corresponding to the captured image and itswatermark is referred to hereinafter as a “watermarked image.” When agroup of captured images are defined, the group of images are referredto hereinafter as an “image group.” When a group of captured images aredefined and watermarked by an embodiment of the image group watermarkingsystem, the group of watermarked images are referred to hereinafter as a“watermarked image group.”

[0016] As used herein, the term “watermark” includes information that isencrypted (embedded) into the pixel data of a selected plurality ofpixels that comprise a digital image. As described in greater detailbelow, such information includes the image digest. The image digest isused to determine if image tampering has occurred. In addition to theimage digest information, the watermark may optionally include otherinformation. Furthermore, the term watermark as used herein furtherincludes information that is incorporated into other parts of the imagedata, such as, but not limited to, the header.

[0017] In one embodiment, watermarking is done by selecting a pluralityof pixels such that the data associated with the selected plurality ofpixels is altered to include the information associated with awatermark. Pixel data in a watermarked image in accordance with thepresent invention may be altered such that a “watermark image” isvisible to a viewer of the image. Alternatively, altered pixel data in awatermarked image in accordance with the present invention may not bevisibly discernible from unaltered pixel data to a viewer of the image.Such watermark information would be detectable electronically.

[0018] Furthermore, for convenience, the term “watermark” is intendedherein to include data that is incorporated into other portions of theimage data associated with an image. Such data may also be referred toherein as encryption data or encrypted data.

[0019] For convenience, an image, a watermarked image, an image groupand/or a watermarked image group, are collectively and/orinterchangeably referred to as “image data” when referencing to thedigital data that corresponds to the image. Depending upon the medium inwhich the image data is stored, processed and/or communicated, theformat of the image data may vary. For example, the format of the imagedata may vary if the image data is communicated over a hardwireconnection, an infrared medium, or a wireless radio frequency medium.Furthermore, image data may be, in some instances, communicated in ananalog data format, such as, but not limited to, instances where theimage data is communicated over a hardwire connection.

[0020] For convenience of teaching the components, operation andfunctionality of the various embodiments of an image group watermarkingsystem, one embodiment of the image group watermarking system isdescribed as being implemented in, or being a part of, a digital camera100 (FIG. 1). The image group watermarking system is equally applicablein any image capture device configured to capture images and generatewatermarked images. For example, but not limited to, a fax machine, acamera film processor, a copy machine, or other device having an imagedetector, are alternative embodiments of an image group watermarkingsystem. Thus, copied and/or communicated images may be captured andwatermarked in accordance with an embodiment of an image groupwatermarking system.

[0021] Another embodiment of an image group watermarking system includesan image detector residing on or within a personal computer tofacilitate video conferencing or to supplement e-mail with picture orvideo information. Accordingly, selected frames from a video arewatermarked by an embodiment of an image group watermarking system inaccordance with the present invention, thereby generating a plurality ofwatermarked images forming a watermarked image group.

[0022] Another embodiment of an image group watermarking system isimplemented in a processing device configured to receive a plurality ofimages and/or at least one image group. That is, this embodiment doesnot include an image capture device. Rather than capturing the images,this embodiment of an image group watermarking system implemented in aprocessing device receives a plurality of previously captured imagesand/or at least one image group, and adds a watermark to each of theimages in accordance with the present invention. For convenience ofteaching the components, operation and functionality of the image groupwatermarking system, this embodiment is described as being implementedin, or being a part of, a personal computer 200 (FIG. 2). Thisembodiment is equally applicable to any processing device configured toreceive a plurality of images and/or at least one image group, andfurther configured to generate a plurality of watermarked images and/orat least one watermarked image group. For example, but not limited to, amainframe processor, or an image processor, or a specially fabricatedperipheral device are alternative embodiments of an image groupwatermarking system.

[0023] Another embodiment of the image group watermarking system,described in greater detail below, is implemented in a processing deviceconfigured to analyze at least one watermarked image group. Thewatermarked images corresponding to watermarked image group inaccordance with the present invention, are analyzed by an embodiment ofan image group watermarking system, as described in greater detailbelow. For convenience of teaching the components, operation andfunctionality of this embodiment of the image group watermarking system,this embodiment is described as being implemented in, or being a partof, a personal computer 200 (FIG. 2). Furthermore, but not limited to, amainframe processor, or an image processor, or a specially fabricatedperipheral device are alternative embodiments.

[0024]FIG. 1 is a block diagram of an embodiment of an image groupwatermarking system 10 implemented in a digital camera 100. FIG. 1illustrates selected external and internal components, separated bycut-away lines 102. Internal components of the digital camera 100 areillustrated between the two cut-away lines 102. Internal componentsinclude at least a memory element 104 storing the watermarking system106 and a camera image data region 108. The watermarking system 106includes at least a watermark encryption logic 110 and a first imageencryption key 112. Other internal components include a camera processor114 and a photosensor 116. In one embodiment of digital camera 100employing a memory module unit 224 (FIG. 2), described in greater detailbelow, digital camera 100 may include a memory storage interface 118.

[0025] Cut-away lines 102 demark components residing on the outsidesurfaces of the digital camera 100 and components residing internally inthe digital camera 100. Thus, control button 120, lens unit 122, imagecapture actuation button 124, power switch 126, viewing lens 128,plug-in interface 130, memory unit interface 132 and display 134 arerecognized as components residing on the surfaces of digital camera 100.

[0026] As described in greater detail herein, control button 120 isactuated to cause the digital camera 100 to operate in an image groupwatermarking mode of operation. Thus, when not operating in an imagegroup watermarking operating mode, images are captured withoutwatermarking as described herein in accordance with the presentinvention. When control button 120 is actuated, captured images aredefined into an image group and watermarked as described herein. Thus,the activation of an image group watermarking system 10 while thedigital camera 100 is operating is optional. The image groupwatermarking system 10 is activated when a user selects the image groupwatermarking mode of operating the digital camera 100 by actuatingcontrol button 120. In other embodiments, control button 120 may be aspecially dedicated controller device, such as a control button, apush-button, a switch or the like. In another embodiment, thefunctionality of control button 120 is incorporated into anothermulti-function controller. In yet another embodiment, the image groupwatermarking mode of operating is effected via a menu system shown ondisplay 134.

[0027] Photosensor 116 is disposed in a suitable position behind thelens unit 122 such that an image (not shown) is focused onto thephotosensor 116 for capturing. Photosensor 116 provides informationcorresponding to the detected image to the camera processor 114, viaconnection 136.

[0028] Display 134 is used for previewing images prior to capturing, forviewing captured images, and/or for viewing information for controllingthe operation of the digital camera. For convenience of illustration,the display 134 is illustrated as residing on the top of the digitalcamera 100. When the digital camera 100 is operating in a mode thatdisplays the image currently detected by photosensor 116 on display 134,the displayed image is hereinafter referred to as a preview image.

[0029] The user of the digital camera 100 can preview a detected currentimage to determine if the user wants to “photograph” the detectedcurrent image. If so, the user of the digital camera 100 actuates theimage capture actuation button 124 such that camera processor 114transfers the received image information from the photosensor 116 intothe camera image data region 108 of memory element 104. That is, whenthe user actuates image capture actuation button 124, camera processor114 reformats the current image detected by photosensor 116 into a imagethat is suitable for storage into memory element 104, via connection138. As the user of digital camera 100 continues with the process of“photographing” images, a plurality of images corresponding to aplurality of captured images is stored into the camera image data region108 of memory element 104.

[0030] Once a plurality of images have been captured and stored intomemory, the user of digital camera 100 may selectively recall capturedimages from memory for viewing. When the digital camera 100 is operatingin a mode that displays previously captured images on display 134, thedisplayed image is hereinafter referred to as a review image.

[0031] In one embodiment, plug-in interface unit 130 includes aplurality of connection pins 140 to facilitate mating of plug-inattachment 218 (FIG. 2) and plug-in interface unit 130, and to provideconnectivity between connection 216 and digital camera 100. Otherembodiments employ other suitable connectors.

[0032]FIG. 2 is a block diagram of an embodiment of image groupwatermarking system 10 implemented in a digital camera 100, and anotherembodiment of image group watermarking system 10 implemented in personalcomputer 200. Personal computer 200 includes at least memory element 202storing image group watermark detection logic 204, image data region 206and key region 208. Also included is at least processor 210, wireconnector interface 212 and memory module interface 214.

[0033] Personal computer 200 receives a watermarked image group fromdigital camera 100 in accordance with the present invention. In oneembodiment of the image group watermarking system 10, the receivedwatermarked image group is stored in image data region 206. Encryptionkeys according to the present invention, and described in greater detailbelow, are stored in key region 208. Alternatively, other embodiments ofthe image group watermarking system 10 store the encryption key inanother suitable location within memory element 202, or in anothersuitable memory device.

[0034] In one mode of operation, digital camera 100 transfers thewatermarked image group to personal computer 200 via connection 216. Forconvenience, connection 216 is illustrated as a hardwire connectioncoupled to the plug-in attachment 218. Connection 216 may be anysuitable connection device employing a communication medium suitable forcommunicating data, such as, but not limited to a universal serial bus(USB), serial connection, parallel connection, wireless radio frequency,and wireless infrared. The plug-in attachment 218 is configured to matewith the plug-in interface unit 130 (FIG. 1). The user of the personalcomputer 200 and the digital camera 100 mates the plug-in attachment 218to the plug-in interface unit 130 thereby establishing connectivitybetween the digital camera 100 and the personal computer 200. The userthen instructs the personal computer 200 and/or digital camera 100 toexecute logic such that at least one watermarked image group istransferred from the digital camera 100, via connection 142, throughplug-in interface 130, connection 216 and wire connector interface 212.Once personal computer 200 receives the watermarked image group, thewatermarked image group is transferred to processor 210, via connection220, and then into the image data region 206 of memory element 202, viaconnection 222.

[0035] In another embodiment of an image group watermarking system 10,digital camera 100 stores image data (one or more images and/or at leastone watermarked image group) in memory module unit 224. Memory moduleunit 224 includes at least an image memory region 226 for storing theimage data, and a first image encryption key 228 in accordance with thepresent invention. Memory module unit 224 is coupled to the digitalcamera 100 through the memory unit interface 132, as illustrated by thepath of insertion represented by dashed line 230. Accordingly, when theuser actuates the image capture actuation button 124 such that cameraprocessor 114 transfers the detected image from the photosensor 116 tothe camera processor 114, the image data is communicated into the imagememory region 226. In one embodiment, a image data is communicated fromcamera processor 114 to memory storage interface 118, via connection146, such that the image data is formatted into a data format that iscompatible with memory module unit 224. In another embodiment, cameraprocessor 114 provides suitably formatted image data directly to thememory module unit 224, via connections 144 and 146. Accordingly, suchan embodiment does not employ memory storage interface 118.

[0036] Memory module unit 224 may be formatted in various ways, such as,but not limited to, a standard computer disk, a floppy disc, a compactdisk (CD), a mini-compact disk, or other suitable memory medium. Imagedata is transferred to the personal computer 200 by removing the memorymodule unit 224 from the digital camera 100 and coupling the memorymodule unit 224 to personal computer 200 by inserting memory module unit224 into the memory module interface 214, as illustrated by the path ofinsertion represented by dashed line 232. In one embodiment, aconvenient coupling port or interface (not shown) is provided on thesurface of personal computer 200 such that the memory module unit 224 isdirectly coupled to the personal computer 200. Once the memory moduleunit 224 is connectively coupled to the memory module interface 214,image data is transferred to the processor 210, via connection 234, andto the image data region 206 of memory element 202, via connection 222.

[0037] For convenience, digital camera 100 is illustrated as employingboth a plug-in interface 130 configured to connectively couple to aphysical connector 216 and a memory unit interface 132 configured toreceive memory module unit 224. Other embodiments of digital camera 100employ either plug-in interface 130 or a memory unit interface 132 tofacilitate the transfer of image data to personal computer 200.

[0038] For convenience, personal computer 200 and digital camera 100 areillustrated as having only selected components of interest. However,personal computer 200 and digital camera 100 include additional internalcomponents not illustrated in FIGS. 1 and 2.

[0039]FIG. 3 illustrates four watermarked images 302, 304, 306 and 308having watermarks in accordance with an embodiment of the image groupwatermarking system 10. Each watermark includes at least an image digestfor the watermarked image and a decryption key for the next watermarkedimage in the watermarked image group.

[0040] The image digest is used for determining if at least one of thewatermarked images in a watermarked image group has been removed,replaced, forged, tampered with, altered, or otherwise corrupted. Thus,security of each individual watermarked image in the watermarked imagegroup is provided.

[0041] As described in greater detail below, the image decryption key isused for decrypting at least the watermark of the next watermarked imagein the watermarked image group. When the watermark of the nextwatermarked image is read or otherwise inspected, the decryption keynecessary to decrypt the watermark must be obtained from the priorwatermarked image. In one embodiment, this decryption key exists only inthe watermark of the previous watermarked image. No other record oroccurrence of the decryption key exists. Thus, if one of the watermarkedimages in the watermarked image group, watermarked in accordance withthe present invention, is removed, replaced, forged, tampered with,altered, or otherwise corrupted, the watermark for the next watermarkedimage cannot be determined. Accordingly, a person will understand thatthe prior watermarked image has been removed, replaced, forged, tamperedwith, altered, or otherwise corrupted.

[0042] For convenience, the four watermarked images 302, 304, 306 and308 are used to describe the components, operation and functionality ofembodiments of a image group watermarking system 10. The image groupwatermarking system 10 is equally applicable with watermarked imagegroups having two, three, five, or any other number of watermarkedimages.

[0043] In FIG. 3, an embodiment of the image group watermarking system10 has watermarked the four images 302, 304, 306 and 308. Accordingly,the first watermarked image 302 includes at least a first watermark 310having at least a first image digest 312 and a second image decryptionkey 314. The second image decryption key 314 is necessary to decrypt atleast the second water mark 316 of the second watermarked image 304. Inan alternative embodiment, the second image decryption key 314 isnecessary to decrypt both the second water mark 316 and the secondwatermarked image 304.

[0044] Similarly, the second watermarked image 304 includes at least asecond watermark 316 having at least a second image digest 318 and athird image decryption key 320. The third image decryption key 320 isnecessary to decrypt at least the third water mark 322 of the thirdwatermarked image 306. In an alternative embodiment, the third imagedecryption key 320 is necessary to decrypt both the third water mark 322and the third watermarked image 306.

[0045] The third watermarked image 306 includes at least a thirdwatermark 322 having at least a third image digest 324 and a fourthimage decryption key 326. The fourth image decryption key 326 isnecessary to decrypt at least the fourth water mark 328 of the fourthwatermarked image 308. In an alternative embodiment, the fourth imagedecryption key 326 is necessary to decrypt both the fourth water mark328 and the fourth watermarked image 308.

[0046] The fourth watermarked image 308 includes at least a fourthwatermark 328 having at least a fourth image digest 330 and a firstimage decryption key 332. The first image decryption key 332 isnecessary to decrypt at least the first water mark 310 of the firstwatermarked image 302. In an alternative embodiment, the first imagedecryption key 332 is necessary to decrypt both the first water mark 310and the first watermarked image 302.

[0047] Accordingly, and as illustrated by the four watermarked images302, 304, 306 and 308, decryption key for the next watermarked image arecoded into each watermark. Thus, if one of the watermarked images areremoved, altered or replaced with a forgery, the watermark of the nextwatermarked image can not be decrypted because the necessary decryptionkey is not available. In an embodiment that required the decryption keyfor decrypting both the image and the watermark, the next image cannotbe analyzed at all since the image cannot be decrypted. One embodiment,upon determining that one of the watermarked images or its associatedwatermark cannot be decrypted, generates a corruption message. Forexample, but not limited to, the corruption message in one embodimentidentifies the watermarked image that is missing, specifies thewatermarked image that is tampered with, specifies the watermarked imagethat is altered, or specifies the watermarked image that has beenreplaced with a forgery.

[0048] Digital camera 100, in one embodiment, is configured to capture aplurality of images and store a corresponding plurality of images in thecamera image data region 108 (FIG. 1). When the user of the digitalcamera 100 is ready to create a watermarked image group in accordancewith the present invention, the user selects the images that are tocomprise the watermarked images in the watermarked image group. The userselects images for watermarking (and their order in the image group) byactuation of control button 120. Once the image group has been defined,actuation of control button 120, or another suitable controller, causesthe images to be watermarked in accordance with the present invention.As noted above, the functionality of control button 120 may beimplemented in a variety of suitable controller devices.

[0049] In one embodiment, the user specifies the order of the selectedimages that will be used to create the watermarked image group. That is,the user specifies a image group. Thus, the user associates a number,letter, tag or other suitable identifier with each selected image. Inanother embodiment, images are ordered according to the order that theuser selects the images. In another embodiment, images are orderedaccording to the order that the user captures the images. In yet anotherembodiment, images are ordered according to the time that the imageswere captured. As described above, the images are not yet watermarked inaccordance by an embodiment of an image group watermarking system 10.Accordingly, one embodiment allows the user to alter, add, delete orreorder the images in the specified image group. For example, the usermay wish to add a date/time stamp, or other suitable meta-data, to theimage before the image is watermarked in accordance with the presentinvention. Preferably, the above-described control button 120 isconfigured such that actuation of control button 120 allows the user ofdigital camera 100 to specify images that are to be watermarked by thewatermark encryption logic 110.

[0050] An alternative embodiment of the image group watermarking system10 implemented in digital camera 100 watermarks images as the images arecaptured. When control button 120 is actuated, digital camera 100 iscaused to operate in an image group watermarking mode of operation.Thus, subsequently captured images are known to be images that are to bewatermarked by the watermark encryption logic 110. Accordingly, as thenext image is captured, the captured image is immediately watermarked bythe watermark encryption logic 110. As described herein, a decryptionkey for the next captured image is determined at the time the currentimage is captured such that the determined decryption key (for the nextcaptured image) is encrypted into the current captured image as it iswatermarked. Control button 120 is later actuated to indicate that thenext image captured is to be the last captured image of the watermarkedimage group. Thus, the next captured image is watermarked in accordancewith the present invention. The digital camera 100 then returns to itsprevious mode of operation (or another predefined mode of operation).

[0051] Another embodiment of the image group watermarking system 10implemented in personal computer 200 includes an embodiment of thewatermark encryption logic 110. Such an embodiment of the watermarkencryption logic 110 is configured to receive a plurality of previouslycaptured images residing in image data region 206 of memory element 202,camera image data region 108 of memory element 104, image memory region226 of memory module unit 224, or another remote memory configured tostore captured images. Such an embodiment is particularly suited forgenerating a watermarked image group from previously captured imagesand/or from images captured from a plurality of image capture devices.

[0052] For example, but not limited to, a crime scene may beinvestigated by a plurality of investigators each having their own imagecapture device. Captured images of the crime scene, captured by theplurality of image capture devices, may be later aggregated together andwatermarked such that a watermarked image group is generated inaccordance with the present invention. Furthermore, other documents orimages of interest copied by other types of image capture devices (copymachines, FAX machines, etc.) that generate digital images arewatermarked and included in a watermarked image group in accordance withthe present invention. Thus, watermarked images associated with theinvestigated crime scene are compiled into a watermarked image groupsuch that image tampering to any of the watermarked images in thewatermarked image group is detectable.

[0053] The image digest is comprised of any suitable informationidentifying the originality of an image such that an image may bedetermined to be the original image. Meta data may also be included inthe image digest. For example, but not limited to, the meta data mayinclude the identity of the individual capturing the image, the identityand/or location of a sender and/and or an intended recipient of theimage if the image group is communicated, the date and/or time when theimage was captured or when the image group was communicated, or otherinformation of interest.

[0054] Once the user has selected and/or ordered the images of the imagegroup, the user prompts the above-described camera processor 114(FIG. 1) or the above-described processor 210 (FIG. 2) to execute thewatermark encryption logic 110. At least two functions are performed foreach image such that a watermarked image is generated. Each image isanalyzed such that an image digest, described in greater detail below,is created and associated with the image. An image decryption key isspecified for the next image in the image group. At least thisabove-described information (image digest and next image decryption key)is included in the watermark for that image.

[0055] Accordingly, the watermark encryption logic 110 defines anencrypting key for a image, and then encrypts the watermark and insertit into the image, thus creating a watermarked image. After thewatermark is encrypted, the encryption key is destroyed. Thus, even ifthe watermark of the watermarked image can be decrypted, it is notpossible for a tampered-with or forged watermark to be re-encrypted andinserted into the image because the tampered-with or forged watermarkmust be decrypted using the decryption key from the previous watermarkedimage in the watermarked image group. Thus, tampering with the watermarkor forging the watermark results in the chain of watermarked imagesbeing broken such that the tampering or forgery is detected.

[0056] As will be described in greater detail below, the image digestcreated from each image is used to determine if an image has beenremoved, replaced, altered, tampered with and/or forged. Any suitableanalysis technique, generally known as hashing, is used in oneembodiment to create the digest containing the defining characteristicsof the image. Examples of hash functions include checksums, cyclicredundancy codes (CRCs), etc. Thus, if the image digest of areplacement, altered, tampered-with or forged image is compared with theimage digest of the original image, the two image digests will bedifferent. A difference in image digests indicates a replacement;altered, tampered-with or forged image.

[0057] Alternative embodiments of an image group watermarking system 10employ other techniques in analyzing an image. For example, only thewatermark itself, or a plurality of watermarks, or a pattern ofwatermarks may be analyzed. Or, another embodiment analyzes selectedportions of the image. The image group watermarking system 10 is equallyapplicable to any form of image analysis that is used to define thecharacteristics of an original image and/or its watermark(s).Accordingly, the determined characteristics of a image and/or itswatermark(s) are referred to herein as the image digest.

[0058] As described above, the watermark encryption logic 110 encrypts awatermark and inserts it in each one of the selected images of the imagegroup to create watermarked images in a watermarked image group.Watermarks in accordance with the present invention are inserted into animage using any suitable watermarking process, method or technology. Forexample, at least one watermarking technique in accordance with thepresent invention inserts the watermark data into the least significantbits (LSB) of selected pixels. In another embodiment, the watermark datain accordance with the present invention are inserted into the image inthe frequency domain.

[0059] FIGS. 4A-D is a flowchart 400 illustrating a process used by anembodiment of the image group watermarking system 10. Flowchart 400shows the architecture, functionality, and operation of oneimplementation of a system for watermarking a plurality of images in animage group in accordance with the present invention. In this regard,each block represents a module, segment, or portion of code, whichcomprises one or more executable instructions for implementing thespecified logical function(s). It should also be noted that in somealternative implementations, the functions noted in the blocks may occurout of the order noted in FIGS. 4A-D. For example, two blocks shown insuccession in FIGS. 4A-D may in fact be executed substantiallyconcurrently or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved, as will be furtherclarified hereinbelow.

[0060] It is understood that prior to starting the process illustratedby flowchart 400, a plurality of images have been defined into an imagegroup. Accordingly, with an embodiment of the image group watermarkingsystem 10 implemented in digital camera 100, a plurality of images havebeen captured by the digital camera 100 and stored in memory. Similarly,with an embodiment of the image group watermarking system 10 implementedin personal computer 200, a plurality of images have been accessed froma memory. The plurality of images in the above-described embodimentshave been predefined as an image group.

[0061] The process of watermarking a group of images in an image groupby the image group watermarking system 10 starts at block 402. At block404, a “first” image is received from a memory. Thus, an embodimentimplemented in digital camera 100 retrieves the “first” image from thecamera image data region 108 in memory element 104 or from the imagememory region 226 of memory module unit 224. If implemented in personalcomputer 200, the image is retrieved from the image data region 206 inmemory element 202 or from another suitable memory element that isaccessible by personal computer 200.

[0062] At block 406, the image digest for the “first” image isdetermined and saved. At block 408, an image encryption key for the“first” image is determined. At block 410, a “first” image decryptionkey is determined and saved. At block 412, a “second” image decryptionkey is determined.

[0063] At block 414, the “first” image is watermarked with at least the“first” image digest and the “second” image decryption key encryptedusing the “first” image encryption key. At block 416, the “first” imageencryption key is destroyed. Thus, the “first” image is watermarked withinformation that will be used to verify the originality of the “first”image (the image digest), along with the “second” image decryption keythat will be used to decrypt the “second” image watermark of thepredefined image group. The decryption key for the “first” imagewatermark will be inserted into the last image watermark in oneembodiment.

[0064] At block 418, a “second” image is received. At block 420, a“second” image digest,is determined and saved. At block 422, a “second”image encryption key is determined. At block 424, the “next” imagedecryption key is determined. Then, at block 426, the “second” image iswatermarked with at least the “second” image digest and the “next” imagedecryption key encrypted using the second image encryption key. It isunderstood that at this stage of the process, the “next” image referredto above is the third image of the image group. At block 428, the“second” image encryption key is destroyed.

[0065] The process proceeds to block 430 where the “next” image isreceived. It is understood that at this stage of the process, the “next”image referred to above is the third image of the image group. However,as described in greater detail below, blocks 430 through 442 areconfigured to watermark the remaining images in the predefined imagegroup. Thus, the “next” image is the image currently being watermarked.At block 432, the “next” image digest is determined and saved. At block434, the “next” image encryption key is determined. At block 436, the“next+1” image decryption key is determined (where the phrase “next+1”identifies the image immediately following the image that is currentlybeing watermarked).

[0066] At block 438, the “next” image is watermarked with at least the“next” image digest and the “next+1” image decryption key encryptedusing the “next” image encryption key. At block 440, the “next” imageencryption key is destroyed. At block 442, a determination is madewhether the “last” image of the predefined image group has beenreceived. If not (the NO condition), the process returns to block 430such that the “next” image is received and then watermarked. That is,blocks 430 through 442 are repeated until all but the “last” image hasbeen watermarked. The watermarking of the “last” image is describedbelow.

[0067] If at block 442 the “last” image has been received, the processproceeds to block 444. At block 444, the “last” image digest isdetermined and saved. At block 446, the “last” image encryption key isdetermined. At block 448, the “first” decryption key, determined andsaved at block 410, is retrieved. At block 450, the “last” image iswatermarked with at least the “last” image digest and the “first” imagedecryption key encrypted using the “last” image encryption key. At block452, the “last” image encryption key is destroyed. The process ends atblock 454.

[0068] In an alternative embodiment, the “first” image decryption key isnot encrypted into the “last” image since the “first” image decryptionkey is communicated along with (or separately from) the watermarkedimage group. Thus, the separately provided “first” image decryption keyis used to decrypt the “first” image watermark, as described below.

[0069] However, in the above described embodiment wherein the “first”image decryption key is encrypted into the “last” image, the “first”image decryption key does not need to be separately communicated.Another image decryption key can be separately communicated, therebyimproving security of the watermarked image group. For example, but notlimited to, the “second” image decryption key could be separatelycommunicated. Thus, an individual decrypting an image group watermarkedaccording to the present invention would have to know that the receivedimage decryption key is associated with the second watermarked image ofthe watermarked image group.

[0070] It is understood that in the above described process, the“destroying” of an image encryption key (blocks 416, 428, 440 and 452)means that the encryption key is deleted or otherwise removed from itscurrent memory location and not saved in a memory. Thus, if an imagewatermarked in accordance with the present invention is removed, forged,tampered with, altered, or otherwise corrupted, a replacement imagecannot be generated since the original encryption key cannot bedetermined. Furthermore, since a replacement image cannot be generated,the decryption key for the next watermarked image in an image groupwatermarked in accordance with the present invention is lost such thatthe watermark in the next watermarked image cannot be decrypted.

[0071] Once an image group is watermarked by an embodiment of an imagegroup watermarking system 10, individual watermarked images in thewatermarked image group cannot be removed, replaced, forged, tamperedwith, altered, or otherwise corrupted without detection during thedecryption process. Watermarked images are decrypted by the image groupwatermark detection logic 204. Accordingly, embodiments of the imagegroup watermarking system 10 may be configured to include the imagegroup watermark detection logic 204 along with watermark encryptionlogic 110. For convenience, the image group watermark detection logic204 is illustrated as residing in memory element 202 or personalcomputer 202. The image group watermark detection logic 204 could alsobe included in digital camera 100. Other embodiments of the image groupwatermarking system 10 do not include the image group watermarkdetection logic 204, and are therefore not configured for decryptingwatermarked images. Furthermore, other embodiments of the image groupwatermarking system 10 only include the image group watermark detectionlogic 204 (without the watermark encryption logic 110), and aretherefore limited to decrypting watermarked images. The particularembodiment of an image group watermarking system 10 implemented in aprocessing device such as, but not limited to, personal computer 200, orimplemented in digital camera 100, is based upon the particular purposeand functionality of the device itself. Thus, omitting the image groupwatermark detection logic 204 conserves memory resources. Similarly,omitting the watermark encryption logic 110 in a packaged programconfigured for a personal computer 202 may be desirable under certainproduct marketing strategies.

[0072] FIGS. 5A-C is a flowchart 500 illustrating a process used by anembodiment of the image group watermarking system 10. Flowchart 500shows the architecture, functionality, and operation of oneimplementation of a system for decrypting a plurality of watermarkedimages in a watermarked image group in accordance with the presentinvention. In this regard, each block represents a module, segment, orportion of code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat in some alternative implementations, the functions noted in theblocks may occur out of the order noted in FIGS. 5A-C. For example, twoblocks shown in succession in FIGS. 5A-C may in fact be executedsubstantially concurrently or the blocks may sometimes be executed inthe reverse order, depending upon the functionality involved, as will befurther clarified hereinbelow.

[0073] It is understood that prior to starting the process illustratedby flowchart 500, a plurality of watermarked images in a watermarkedimage group reside in a memory and are accessible by the processingdevice that is executing the image group watermark detection logic 204.Accordingly, with an embodiment of the image group watermarking system10 implemented in digital camera 100 having the image group watermarkdetection logic 204, a plurality of images have been captured by thedigital camera 100, have been defined as an image group, watermarked inaccordance with the present invention, and stored in memory awatermarked image group. Similarly, with an embodiment of the imagegroup watermarking system 10 having the image group watermark detectionlogic 204 implemented in personal computer 200, a watermarked imagegroup can be accessed from a memory.

[0074] Furthermore, the “first” image decryption key is also accessiblefrom a memory so that the “first” watermark of the watermarked imagegroup can be decrypted. Thus, if the image group watermark detectionlogic 204 is executed by processor 210 residing in personal computer100, the “first” image decryption key has been communicated to thepersonal computer 200 and stored in the key region 208 of memory 202 (orin another suitable location or memory unit). In another embodiment, the“first” image decryption key would be accessed from the first imageencryption key 112 region of memory 104, or from the first imageencryption key region 220 or memory module unit 224, when the digitalcamera 100, or the memory module unit 224, respectively, is coupled topersonal computer 200.

[0075] Alternatively, the “first” decryption key may be securelyretained in the first image encryption key 112 region of memory 104, orsecurely retained in the first image encryption key region 220 or memorymodule unit 224. Thus, decryption of watermark in the watermarked imageswould require that the digital camera 100 or the memory module unit 224be coupled to personal computer 200, thereby improving overall securityof the watermarked image group.

[0076] Also, the image digests of the watermarked images are accessiblefrom a memory so that when the watermark is retrieved from thewatermarked images and decrypted to determine an image digest, thedetermined image digest can be compared to the retrieved image digest.Differences between the determined and retrieved image digests for animage would indicate that the image has been removed, replaced, forged,tampered with, altered, or otherwise corrupted. If the determined imagedigest is the same as the retrieved image digest, then the image has notbeen removed, replaced, forged, tampered with, altered, or otherwisecorrupted.

[0077] The process of decrypting the watermark from watermarked imagesin a watermarked image group starts at block 502. At block 504, the“first” watermarked image is retrieved from memory. At block 506, the“first” image decryption key and the “first” image digest is retrievedfrom memory. At block 508, the “first” image is processed such that the“first” image watermark is determined. At block 510, the image digestassociated with the “first” image is determined from the “first” imagewatermark.

[0078] At block 512, the determined image digest associated with the“first” image is compared with the retrieved “first” image digest. Atblock 514, a determination is made whether the retrieved “first” imagedigest corresponds to the determined image digest. If the retrieved“first” image digest corresponds to the determined image digest for the“first” image (the YES condition), the process proceeds to block 518. Ifnot (the NO condition), the process proceeds to block 516 such that adetermination is made that the “first” image has been tampered with.

[0079] A corruption message is generated and communicated at block 516in response to determining that the “first” image has been tamperedwith. The specific corruption message generated and communicated may bedone in a variety of manners so long as a individual viewing the firstimage understands that image corruption has occurred. For example, atextual message may be generated and communicated to the viewer. Anotherembodiment may generate and communicate a suitable animation or asuitable graphic image that indicates image corruption. Anotherembodiment may be configured to determine the type, nature and/or extentof image corruption and communicate such information to the viewer. Itis understood that the various forms of the corruption message is nearlylimitless so long as a viewer is informed that image corruption has beendetected by the image group watermarking system 10.

[0080] In one embodiment, the process then proceeds to block 518 wherethe “second” watermarked image is retrieved from memory. At block 520,the “second” image decryption key and the “second” image digest isretrieved from memory.

[0081] At block 522, a determination is made whether the “second” imagewatermark can be decrypted. That is, was a “second” image decryption keysuccessfully retrieved from the decryption of the “first” imagewatermark. If the “second” watermark of the second image can bedecrypted (the YES condition), the process proceeds to block 528. If the“second” watermark cannot be decrypted, the process proceeds to block524 such that a determination is made that the “second” image has beenreplaced or is missing. Also, a suitable corruption message isgenerated. The specific corruption message generated and communicatedmay be done in a variety of manners so long as a individual viewing theimage understands that image corruption has occurred. The process thenends at block 526 (since the “next” decryption key required fordecryption of the “next” image watermark, as described below, can not bedetermined).

[0082] At block 528, the “second” image is processed such that the“second” image watermark is determined. At block 530, the image digestassociated with the “second” image is determined from the “second” imagewatermark.

[0083] At block 532, the determined image digest associated with the“second” image is compared with the retrieved “second” image digest. Atblock 534, a determination is made whether the retrieved “second” imagedigest corresponds to the determined image digest. If the retrieved“second” image digest corresponds to the determined image digest for the“second” image (the YES condition), the process proceeds to block 538.If not (the NO condition), the process proceeds to block 536 such that adetermination is made that the “second” image has been tampered with. Acorruption message is generated and communicated at block 536 inresponse to determining that the “second” image has been tampered with.The specific corruption message generated and communicated may be donein a variety of manners so long as a individual viewing the imageunderstands that image corruption has occurred.

[0084] The process then proceeds to block 538 where the “next”watermarked image is retrieved from memory. At block 540, the “next”image decryption key and the “next” image digest is retrieved frommemory.

[0085] At block 542, a determination is made whether the “next” imagewatermark can be decrypted. That is, was a “next” image decryption keysuccessfully retrieved from the decryption of the “second” image. If the“next” image watermark can be decrypted (the YES condition), the processproceeds to block 548. If the “next” image can not be decrypted, theprocess proceeds to block 544 such that a determination is made that the“next” image has been replaced or is missing. Also, a suitablecorruption message is generated. The specific corruption messagegenerated and communicated may be done in a variety of manners so longas a individual viewing the first image understands that imagecorruption has occurred. The process then ends at block 546 (since the“next” decryption key required for decryption of the “next” image, asdescribed below, can not be determined).

[0086] At block 548, the “next” image is processed such that the “next”image watermark is determined. At block 550, the image digest associatedwith the “next” image is determined from the “next” image watermark.

[0087] At block 552, the determined image digest associated with thedecrypted watermark from the “next” image is compared with the retrieved“next” image digest. At block 554, a determination is made whether theretrieved “next” image digest corresponds to the determined imagedigest. If the retrieved “next” image digest corresponds to thedetermined image digest for the “next” image (the YES condition), theprocess proceeds to block 558. If not (the NO condition), the processproceeds to block 556 such that a determination is made that the “next”image has been tampered with. A corruption message is generated andcommunicated at block 556 in response to determining that the “next”image has been tampered with. The specific corruption message generatedand communicated may be done in a variety of manners so long as aindividual viewing the first image understands that image corruption hasoccurred.

[0088] At block 558, a determination is made whether the “last” imagewatermark of the predefined image group has been decrypted. If not (theNO condition), the process returns to block 538 such that the “next”image is received and then processed. That is, blocks 538 through 558are repeated until all but the “last” image watermark has been decryptedand processed (assuming no image tampering).

[0089] If the last image watermark has been decrypted and processedsuccessfully (the YES condition), the process ends at block 560. Thatis, the current image being processed (the current “next” image) is, infact, the last watermarked image in the watermarked image group.

[0090] The above-described process presumes that the “first” imagedecryption key was provided such that the process of decryptingwatermarks from watermarked images began with the “first” watermarkedimage. Thus, the watermarked image group processed above could begenerated by an embodiment of the watermark encryption logic 110 thatinserts the “first” image decryption key into the “last” imagewatermark, or by an embodiment of the watermark encryption logic 110that does not insert the “first” image decryption key into the “last”watermarked image.

[0091] An alternative embodiment of the image group watermark detectionlogic 204 is configured to allow the watermark decryption process tostart with any one of the watermarked images. For example, oneembodiment described above saved the “second” image decryption key. This“second” image decryption key would be communicated together orseparately to the individual verifying the integrity of the watermarkedimage group. Thus, the first image watermark decrypted would be the“second” watermarked image. The other watermarks would be, in-turn,decrypted until all watermarks are decrypted in accordance with thepresent invention.

[0092] The image group watermark detection logic 204 and/or thewatermark encryption logic 110 of the various above-describedembodiments of the image group watermarking system 10 can be implementedin software (e.g., firmware), hardware, or a combination thereofresiding in memory elements 104 and/or 202 . When the image groupwatermark detection logic 204 and/or the watermark encryption logic 110is implemented in software, the logic may be an executable program thatis executed by a special and/or a general purpose computer, such as, butnot limited to, a personal computer 200 (PC; IBM-compatible,Apple-compatible, or otherwise), workstation, minicomputer, and amainframe computer. The camera processor 114 and/or processor 210 is ahardware device for executing software, particularly that stored inmemory elements 104 and/or 202. The camera processor 114 and/orprocessor 210 can be any custom made or commercially available cameraprocessor and/or personal computer processor, a central processing unit(CPU), an auxiliary processor among several processors associated withthe personal computer 200 and/or digital camera 100, a semiconductorbased microprocessor (in the form of a microchip or chip set), amicroprocessor, or generally any device for executing softwareinstructions. Examples of suitable commercially availablemicroprocessors include: a PA-RISC series microprocessor fromHewlett-Packard Company, an 80x86 or Pentium series microprocessor fromIntel Corporation, a PowerPC microprocessor from IBM, a Sparcmicroprocessor from Sun Microsystems, Inc, or a 68xxx seriesmicroprocessor from Motorola Corporation.

[0093] The memory elements 104 and/or 202 can include any one orcombination of volatile memory elements (e.g., random access memory(RAM, such as DRAM, SRAM, SDRAM, etc.) and nonvolatile memory elements(e.g., ROM, hard drive, tape, CDROM, etc.). Moreover, memory elements104 and/or 202 may incorporate electronic, magnetic, optical, and/orother types of storage media. Note that the memory elements 104 and/or202 can have a distributed architecture, where various components aresituated remote from one another, but can be accessed by the cameraprocessor 114 and/or the processor 210.

[0094] Embodiments of the image group watermark detection logic 204and/or the watermark encryption logic 110 may be a source program,executable program (object code), script, or any other entity comprisinga set of instructions to be performed. When a source program, then theprogram needs to be translated via a compiler, assembler, interpreter,or the like, which may or may not be included within the memory element104 and/or 202, so as to operate properly in connection with anoperating system. Furthermore, the image group watermark detection logic204 and/or the watermark encryption logic 110 can be written as (a) anobject oriented programming language, which has classes of data andmethods, or (b) a procedure programming language, which has routines,subroutines, and/or functions, for example but not limited to, C, C++,Pascal, Basic, Fortran, Cobol, Perl, Java, and Ada.

[0095] When the image group watermark detection logic 204 and/or thewatermark encryption logic 110 is implemented in software, as is shownin FIG. 2, it should be noted that the image group watermark detectionlogic 204 and/or the watermark encryption logic 110 can be stored on anycomputer readable medium for use by or in connection with any computerrelated system or method.

[0096] In the context of this document, a computer readable medium is anelectronic, magnetic, optical, or other physical device or means thatcan contain or store a computer program for use by or in connection witha computer related system or method. The image group watermark detectionlogic 204 can be embodied in any computer-readable medium for use by orin connection with an instruction execution system, apparatus, ordevice, such as a computer-based system, processor-containing system, orother system that can fetch the instructions from the instructionexecution system, apparatus, or device and execute the instructions. Inthe context of this document, a “computer-readable medium” can be anymeans that can store, communicate, propagate, or transport the programfor use by or in connection with the instruction execution system,apparatus, or device. The computer readable medium can be, for examplebut not limited to, an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, apparatus, device, or propagationmedium. More specific examples (a nonexhaustive list) of thecomputer-readable medium would include the following: an electricalconnection (electronic) having one or more wires, a portable computerdiskette (magnetic, flash), a random access memory (RAM) (electronic), aread-only memory (ROM) (electronic), an erasable programmable read-onlymemory (EPROM, EEPROM, or Flash memory) (electronic), an optical fiber(optical), and a portable compact disc read-only memory (CDROM CD, DVD,etc.) (optical). Note that the computer-readable medium could even bepaper or another suitable medium upon which the program is printed, asthe program can be electronically captured, via for instance opticalscanning of the paper or other medium, then compiled, interpreted orotherwise processed in a suitable manner if necessary, and then storedin a computer memory.

[0097] In an alternative embodiment, where the image group watermarkdetection logic 204 and/or the watermark encryption logic 110 isimplemented in hardware, the logic can implemented with any or acombination of the following technologies, which are each well known inthe art: a discrete logic circuit(s) having logic gates for implementinglogic functions upon data signals, an application specific integratedcircuit (ASIC) having appropriate combinational logic gates, aprogrammable gate array(s) (PGA), a field programmable gate array(FPGA), etc.

[0098] It should be emphasized that the above-described embodiments ofthe present invention are merely possible examples of implementations,merely set forth for a clear understanding of the principles of theinvention. Many variations and modifications may be made to theabove-described embodiment(s) of the invention without departingsubstantially from the spirit and principles of the invention. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and the present invention and protected bythe following claims.

Therefore, having thus described the invention, at least the followingis claimed:
 1. A method protecting the integrity of a group of images,the method comprising the steps of: watermarking each one of a pluralityof images in an image group with a unique watermark having at least animage digest, the image digest comprising information that identifiesthe watermarked image as an original image, and the plurality of imageshaving a predefined order in the image group; and including in selectedones of the unique watermarks a unique decryption key, each one of theunique decryption keys configured for decrypting the unique watermark ofa next image in the image group.
 2. The method of claim 1, wherein thestep of including in selected ones of the unique watermarks the uniquedecryption key further comprises the step of watermarking all of theplurality of images in the image group with the unique watermark havingthe unique decryption key of the next image in the image group, andwherein a first image in the image group is defined as the next imagefor a last image of the image group.
 3. The method of claim 1, whereinthe step of watermarking selected ones of the plurality of images withthe unique watermark having the unique decryption key further comprisesthe step of watermarking all but the last image of the plurality ofimages with the unique watermark having the unique decryption key of thenext image in the image group.
 4. The method of claim 1, furthercomprising the step of saving into a memory each one of the imagedigests associated with the plurality of images in the image group. 5.The method of claim 1, further comprising the step of saving a selecteddecryption key, the selected decryption key being selected from theplurality of unique decryption keys.
 6. The method of claim 1, furthercomprising the step of retrieving the image group from a memory.
 7. Themethod of claim 6, further comprising the step of defining the order ofthe plurality of images in the image group such that the plurality ofimages are sequentially ordered.
 8. The method of claim 7, furthercomprising the step of actuating a controller residing on an imagecapture device such that a captured image is defined as a member of theimage group.
 9. The method of claim 1, further comprising the steps of:capturing a plurality of images with an image capture device; andactuating a controller residing on the image capture device such that atleast one next captured image is defined as a member of the image group.10. The method of claim 1, further comprising the steps of: defining atleast one encryption key; and encrypting the unique watermark having theimage digest and the unique decryption key for the next image using thedefined encryption key.
 11. The method of claim 10, further comprisingthe step of destroying the encryption key after the step of encryptingis complete.
 12. A method determining the integrity of a group ofimages, the method comprising the steps of: retrieving a plurality ofwatermarked images, the plurality of watermarked images residing in awatermarked image group and having a predefined order in the watermarkedimage group; retrieving a first decryption key, the first decryption keycorresponding to a selected one of the plurality of watermarked images;decrypting a unique watermark from the selected watermarked image usingthe retrieved first decryption key such that a first image digest isdetermined and a next image decryption key is determined; retrieving anoriginal first image digest associated with the selected watermarkedimage; comparing the original first image digest with the determinedfirst image digest to determine the integrity of the selectedwatermarked image; decrypting a next unique watermark from a nextwatermarked image with the next image decryption key, the nextwatermarked image being the following image in the plurality of orderedwatermarked images; retrieving an original next image digest associatedwith the next watermarked image; comparing the original next imagedigest with the determined next image digest to determine the integrityof the next watermarked image; and repeating the steps of decrypting thenext unique watermark from the next watermarked image, retrieving theoriginal next image digest and comparing the original next image digestfor the remaining plurality of watermarked images.
 13. The method ofclaim 12, further comprising the step of retrieving a first image fromthe ordered plurality of watermarked images such that the retrievedfirst image is associated with the retrieved first decryption key andthe original first image digest.
 14. The method of claim 12, furthercomprising the step of decrypting the unique watermark from a firstimage from the ordered plurality of watermarked images using the nextdecryption key decrypted from the unique watermark of a last image inthe ordered plurality of watermarked images.
 15. The method of claim 12,wherein a first watermarked image of the plurality of orderedwatermarked images in the watermarked image group is defined as the nextimage for a last watermarked image of the watermarked image group. 16.The method of claim 12, further comprising the step of generating animage corrupted message when the step of comparing the original firstimage digest with the determined first image digest determines that theoriginal first image digest is different from the determined first imagedigest.
 17. The method of claim 12, further comprising the step ofgenerating an image corrupted message when the step of comparing theoriginal next image digest with the determined next image digestdetermines that the original next image digest is different from thedetermined next image digest.
 18. The method of claim 12, furthercomprising the step of stopping the steps of decrypting the uniquewatermark from the next watermarked image, retrieving the original nextimage digest and comparing the original next image digest when a currentwatermarked image cannot be decrypted to retrieve the next imagedecryption key.
 19. A system which protects the integrity of a group ofimages using an image capture device, comprising: a photosensorconfigured to capture an image; a memory configured to store a pluralityof captured images; an actuator configured to define selected ones ofthe captured images as a member of an image group; and a processorconfigured to watermark each one of the selected captured images with aunique watermark having at least an image digest that identifies theselected captured image, and the unique watermark further having aunique decryption key that is configured to decrypt the unique watermarkof next one of the selected captured images.
 20. The system of claim 19,wherein the processor is further configured to save the image digest foreach one of the watermarked selected captured images into the memory,and is further configured to save one of the decryption keys.
 21. Thesystem of claim 19, wherein the image capture device comprises at leastone selected from a group consisting of a digital camera, a facsimilemachine and a copy machine.
 22. A system which protects the integrity ofan image group having a plurality of images in a predefined order in theimage group, comprising: means for watermarking each one of a pluralityof images in an image group with a unique watermark having at least animage digest, the image digest comprising information that identifiesthe watermarked image as an original image; and means for including inselected ones of the unique watermarks a unique decryption key, each oneof the unique decryption keys configured for decrypting the uniquewatermark of a next image in the image group.